The present invention relates to a manufacturing method of high purity copper sulfate which includes the steps of dissolving commercially available copper sulfate crystals (purity, for instance, is 95 to 99.9 wt %) in purified water, performing thermal concentration thereto, and filtering out the crystals precipitated initially to eliminate the impurities, and to the high purity copper sulfate obtained thereby. The starting material does not have to be copper sulfate crystal, and may be a material in which copper is dissolved with acid containing sulfuric acid, or copper sulfate crystals manufactured therefrom.
Although copper sulfate (Cu2SO4) is white-colored powder, Hydrous copper sulfate (Cu2SO4-5H2O) is the general term thereof, and this is an azurite blue crystal.
Copper sulfate is used as an electrolytic solution, pigment, insecticide, antiseptic, mordant, battery material, pharmaceutical and so on. In particular, when it is to be used as the electroplating solution in electronic components such as a semiconductor device, high purity copper sulfate is being sought.
Commercially available copper sulfate has a purity level of 95 to 99.9 wt %, and it is necessary to purify this even further to obtain a level of 4N to 5N or more.
As conventional technology, described is a method to obtain copper sulfate with low Ni content by using electrolytic copper powder recovered from an electrolytic solution via electrodeposition as the raw material, immersing this into an acid solution to selectively dissolve and remove Ni, dissolving the filtered copper powder in sulfuric acid, and subjecting this to crystallization (for example, c.f. Japanese Patent Laid-Open Publication No. 2001-10817).
Further, disclosed is technology for obtaining copper sulfate with low nickel content by employing an aqueous solution of copper sulfate containing nickel and heating this to 80° C. or higher, collecting the copper sulfate crystal separated and sedimented, and concentrating this to effect recrystallization (for example, c.f. Japanese Patent Laid-Open Publication No. 2001-31419).